Pleural drainage system and method of use

ABSTRACT

A pleural drainage system having an inflatable membrane and a method of using the system are disclosed. The pleural drainage system includes a pleural drainage catheter system. The pleural drainage catheter system includes an inflatable membrane and a drainage catheter integrally coupled to the inflation membrane, the drainage catheter defining a drainage lumen through which fluid is drawn from the pleural cavity, and an inflation lumen coupled for flow of inflation fluid to and from an interior of the inflatable membrane. The pleural drainage system further includes a suction system coupled to the drainage catheter and a fluid collector coupled to receive fluid from the drainage catheter. The pleural drainage system further includes an inflation system connected to deliver inflation fluid to the interior of the inflatable membrane. The pleural drainage system may be used to monitor an associated airleak in the pleural cavity of a patient.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/160,037, filed Mar. 13, 2009, the contents of whichare incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The field of the invention relates to thoracic systems, and moreparticularly to pleural drainage systems.

BACKGROUND OF THE INVENTION

A number of fluid recovery systems have been developed for withdrawingfluid, such as air and/or blood, from a patient after chest surgery ortrauma. Such systems are intended to remove fluid from the pleural spaceor the mediastinal cavity and to restore the sub-atmospheric pressurethat is normally present in the pleural space. The systems are usuallyadapted to allow suction to be applied to the chest cavity tofacilitate, among other things, the removal of fluid from the pleuralspace. Once the fluid has been removed, the pleural cavity is allowed toheal and the normal condition of the pleural space is restored.

Despite many developments in the field of pleural drainage, thereremains a need for improved pleural drainage systems. Specifically,there remains a need for pleural drainage systems that can provide oneor more of improved drainage of fluid from the pleural cavity of apatient, monitoring of an airleak in a pleural cavity of a patient,and/or the delivery of a therapeutic treatment to the pleural cavity ofa patient.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a pleural drainagecatheter system is provided. The pleural drainage catheter system isconfigured to extend into a pleural cavity of a patient and to drainfluid from the pleural cavity of the patient. The pleural drainagecatheter system includes an inflatable membrane comprising two opposedlayers formed from a bio-compatible material, the inflatable membranehaving a deflated state in which the layers are positioned substantiallyadjacent one another and an inflated state in which at least portions ofthe respective layers are spaced from one another. An external surfaceof the inflatable membrane defines one or more passages that facilitatethe movement of fluid along the external surface for removal from thepleural cavity. The pleural drainage catheter system further includes adrainage catheter integrally coupled to the inflation membrane, thedrainage catheter defining a drainage lumen, a plurality of drainageopenings through which fluid is drawn into the drainage lumen from thepleural cavity, and an inflation lumen coupled for flow of inflationfluid to and from an interior of the inflatable membrane.

According to another aspect of the present invention, a method formonitoring an airleak in a pleural cavity of a patient is provided. Anairleak in a pleural cavity of a patient may be monitored by measuring arate of pressure decay in the pleural cavity of the patient. The rate ofpressure decay is correlated to an associated airleak of the pleuralcavity of the patient according to the following formula:Q_(Airleak)α∫Pdt, where Q_(Airleak) is an extrapolated airleak, P is ameasured pressure, and t is time. An indicator is generated showing atrend in the magnitude of the airleak of the pleural cavity.

According to yet another aspect of the present invention, a pleuraldrainage system is provided. The pleural drainage system is configuredto deliver a therapeutic treatment to the pleural cavity of a patient.The pleural drainage system includes a pleural drainage catheter systemincluding an inflatable membrane having a deflated state and an inflatedstate. The pleural drainage catheter system also includes a drainagecatheter coupled to the inflation membrane, the drainage catheterdefining a drainage lumen, a plurality of drainage openings throughwhich fluid is drawn into the drainage lumen from the pleural cavity,and an inflation lumen coupled for flow of inflation fluid to and froman interior of the inflatable membrane. The pleural drainage systemfurther includes a suction system coupled to the drainage catheter ofthe pleural drainage catheter system and connected to apply suction tothe drainage lumen of the drainage catheter and to draw fluid into thedrainage lumen of the drainage catheter through the drainage openingsdefined by the drainage catheter. The pleural drainage system furtherincludes a fluid collector coupled to receive fluid from the drainagelumen of the drainage catheter. The pleural drainage system furtherincludes an inflation system coupled to the drainage catheter of thepleural drainage catheter system and connected to apply pressure to theinflation lumen of the drainage catheter and to deliver inflation fluidto the interior of the inflatable membrane through the inflation lumendefined by the drainage catheter.

According to still another aspect of the present invention, a pleuraldrainage system includes a drainage catheter, a suction system, a fluidcollector, a pressure sensor, a processor, and a plurality ofindicators. The drainage catheter defines a drainage lumen and at leastone drainage opening through which fluid is drawn into the drainagelumen from a pleural cavity. The suction system is coupled to applysuction to the drainage lumen in order to draw fluid into the drainagelumen through the at least one drainage opening. The fluid collector iscoupled to receive fluid from the drainage lumen of the drainagecatheter. The pressure sensor is coupled to the suction system and ispositioned to sense a pressure in the pleural cavity. The processor iscoupled to receive a signal from the pressure sensor based on the sensedpressure in the pleural cavity. The indicators are coupled to theprocessor and configured to visually indicate a status corresponding tothe sensed pressure in the pleural cavity to an operator. The processoris configured to selectively activate the plurality of indicators suchthat a first indicator of the plurality of indicators is activated whenthe sensed pressure is within a first predefined range, a secondindicator of the plurality of indicator is activated when the sensedpressure is within a second predefined range, and a third indicator ofthe plurality of indicators is activated when the sensed pressure iswithin a third predefined range.

According to another aspect of the present invention, a pleural drainagesystem includes a drainage catheter, a suction system, and a fluidcollector. The drainage catheter defines a drainage lumen and at leastone drainage opening through which fluid is drawn into the drainagelumen from a pleural cavity. The suction system is coupled to applysuction to the drainage lumen in order to draw fluid into the drainagelumen through the at least one drainage opening. The suction systemincludes a pump, an accumulator in fluid communication with the pump,and a valve coupled between the accumulator and the drainage catheter.The fluid collector is coupled to receive fluid from the drainage lumenof the drainage catheter. The pump is configured to generate a negativepressure in the accumulator. The valve is configured to open when thereis a blockage between the pleural cavity and the fluid collector. Theopening of the valve causes the negative pressure in the accumulator tobe applied to the drainage catheter such that the blockage is drawn intothe fluid collector.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawings. It is emphasizedthat, according to common practice, the various features of the drawingsare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawings are the following figures:

FIG. 1 is a perspective view of an exemplary embodiment of a pleuraldrainage catheter system according to an aspect of the presentinvention;

FIGS. 2 a and 2 b are perspective views of another exemplary embodimentof a pleural drainage catheter system according to an aspect of thepresent invention;

FIGS. 3 a and 3 b are perspective and cross-sectional side views of thepleural drainage catheter system shown in FIG. 2 a;

FIGS. 4 a and 4 b are perspective and cross-sectional side views of thepleural drainage catheter system shown in FIG. 2 b, in an inflatedstate;

FIG. 5 is another perspective view of the pleural drainage cathetersystem shown in FIG. 2 b;

FIG. 6 is a cross-sectional end view of another exemplary embodiment ofa pleural drainage catheter system in accordance with an aspect of thepresent invention;

FIG. 7 is a cross-sectional end view of the pleural drainage cathetersystem shown in FIG. 6, in an inflated state;

FIG. 8 is a cross-sectional end view of yet another exemplary embodimentof a pleural drainage catheter system in accordance with an aspect ofthe present invention;

FIG. 9 depicts an embodiment of a pleural drainage catheter systemhierarchy in accordance with an aspect of the present invention;

FIG. 10 is a cross-sectional end view of an exemplary embodiment of apleural drainage catheter system inserted in a pleural cavity of apatient in accordance with an aspect of the present invention;

FIG. 11 is a cross-sectional end view of the pleural drainage cathetersystem shown in FIG. 10, in an inflated state;

FIG. 12 is a side view of the pleural drainage catheter system shown inFIG. 11;

FIG. 13 depicts an embodiment of a pleural drainage system for drainingfluid from the pleural cavity of a patient in accordance with an aspectof the present invention;

FIG. 14 depicts an embodiment of a pleural drainage system hierarchy inaccordance with an aspect of the present invention;

FIG. 15 is a graph depicting measurements of the decay in pressure inthe pleural cavity of a patient as a function of time in accordance withan aspect of the present invention;

FIG. 16 is a graph depicting the trend and rates of pressure decayrelating to an associated patient airleak as a function of time inaccordance with an aspect of the present invention;

FIG. 17 depicts another embodiment of a pleural drainage system fordraining fluid from the pleural cavity of a patient in accordance withan aspect of the present invention;

FIG. 18 depicts a control panel of the pleural drainage system shown inFIG. 17;

FIG. 19 is a schematic diagram illustrating an exemplary arrangement ofelectrical components that can be used in the pleural drainage systemshown in FIG. 17;

FIG. 20 depicts exemplary patient pressure indicators of the controlpanel of the pleural drainage system shown in FIG. 17;

FIG. 21 is a top perspective view of another exemplary embodiment of apleural drainage catheter system according to an aspect of the presentinvention;

FIG. 22 is a bottom perspective view of the pleural drainage cathetersystem shown in FIGS. 21; and

FIG. 23 is a cross-sectional end view of the pleural drainage cathetersystem shown in FIG. 21.

DETAILED DESCRIPTION OF THE INVENTION

This invention will now be described with reference to severalembodiments selected for illustration in the drawings. It will beappreciated that the scope and spirit of the invention are not limitedto the illustrated embodiments. It will further be appreciated that thedrawings are not rendered to any particular proportion or scale. Also,any dimensions referred to in the description of the illustratedembodiments are provided merely for the purpose of illustration. Theinvention is not limited to any particular dimensions, materials, orother details of the illustrated embodiments.

FIG. 1 depicts an exemplary embodiment of a pleural drainage cathetersystem 100 in accordance with an aspect of the present invention. Thepleural drainage catheter system 100 is configured to extend into apleural cavity of a patient (not shown). The pleural drainage cathetersystem 100 includes an inflatable membrane 102 and a drainage catheter104 integrally coupled to inflatable membrane 102. The drainage catheter104 may be centrally located and at least partially surrounded byinflatable membrane 102. Inflatable membrane 102 may further be sealableto enclose drainage catheter 104.

Inflatable membrane 102 is formed from two opposed layers, the twoopposed layers optimally being two thin layers of a bio-compatiblematerial. The bio-compatible material may be, for example, polyurethane,polyester, polyethylene elastomers, mylar, PVC, or other polymericmaterials.

Inflatable membrane 102 defines one or more tubelets 106 when in aninflated state, the embodiment shown including four such tubelets 106extending outwardly from each side of drainage catheter 104, thoughfewer or more such tubelets can be provided. The tubelets 106 may beprovided in the form of substantially straight structures, asillustrated, or in other curved or angled shapes to form inflatableribs. While tubelets 106 are illustrated as primarily straight andcylindrical in shape in this embodiment, it will be understood thattubelets 106 may have other shapes and configurations, as desired.Tubelets 106 may be formed by selectively sealing the two opposed layersof inflatable membrane 102 to define the one or more tubelets 106.

Tubelets 106 may extend in a direction angled with respect to an axis ofdrainage catheter 104. Specifically, tubelets 106 may extend in adirection substantially perpendicular to an axis of drainage catheter104 as illustrated. Inflatable membrane 102 can be inserted into apleural cavity in a deflated or optimally collapsed configuration. Thisallows for the system 100 to be inserted though significantly smalleropenings in the body or through smaller trocar systems than other largerand bulkier tubular devices, thereby reducing tissue trauma andassociated pain and discomfort in recovery. System 100 may also beconfigured for insertion using standard chest tube insertion techniques,as would be known to one of ordinary skill in the art.

Inflatable membrane 102 has a deflated state, in which the inflatablemembrane 102 and the one or more tubelets 106 are deflated. In thisstate, the two opposed layers are positioned substantially adjacent oneanother. Inflatable membrane 102 also has an inflated state, in whichtubelets 106 are inflated. In this state, portions of the respectiveopposed layers forming tubelets 106 are spaced apart from one another.As will be described later in greater detail, inflation fluid such as aninflation gas or liquid is delivered between the layers of the membrane102 to inflate the tubelets 106 and, in turn, to inflate portions of themembrane 102. Though inflatable membrane 102 is illustrated withtubelets 106, other shapes or areas of inflatable membrane 102, or theentire inflatable membrane 102, may receive the inflation fluid toinflate membrane 102.

The external surface of inflatable membrane 102 which forms tubelets 106also defines one or more passages 108 between the tubelets 106. Thepassages 108 may function as drainage channels such that when inflatablemembrane 102 is in the inflated state, passages 108 facilitate themovement of fluid along the external surface of inflatable membrane 102to drainage catheter 104 for removal from the pleural cavity. As will bedescribed later in greater detail, the inflation of the tubelets 106will function to separate tissue in the pleural cavity and to separatetissue from the membrane 102 in locations adjacent and/or between thetubelets 106. In that way, gaps or passages or channels are formed thatfacilitate flow of fluid along or adjacent to surfaces of the membrane102.

Passages 108 or other structures of the membrane 102 optionally define adrainage opening between tubelets 106 for the flow of fluid from aperimeter portion of inflatable membrane 102, or within the perimeter,to drainage catheter 104.

Inflatable membrane 102 may also include radiopaque edges or markers 110along the edges of inflatable membrane 102. The radiopaque markers 110may be positioned to facilitate visualization of inflatable membrane 102during and after its insertion into the pleural cavity of a patient.According to one exemplary embodiment, one or more markers arepositioned along the perimeter of the membrane 102. They can bepositioned intermittently at even or varied spacings or a singlecontinuous marker can circumscribe the entire perimeter. Also, markerscan be positioned at other locations on or along the membrane 102 ordrainage catheter 104 to facilitate visualization. Radiopaque markers110 may include radiopaque alloys such as, for example, gold, platinum,iridium, palladium, rhodium, or a combination of such alloys. Radiopaquemarkers 110 may further include radiopacifier materials such as, forexample, barium sulfate, bismuth, and tungsten.

Further, inflatable membrane 102 may include a protective coating (notshown) on the external surface of inflatable membrane 102. Theprotective coating may be configured to resist adhesion or providetherapy to tissue in the pleural cavity of a patient. Examples ofadhesion-resistant and/or therapeutic coatings and/or therapeuticsinclude, for example, fish oil, omega 3 fatty acids, antiproliferatives,antineoplastics, paclitaxel, rapamyacin, hyaluronic acid, humanplasma-derived surgical sealants, and agents comprised of hyaluronateand carboxymethylcellulose that are combined with dimethylaminopropyl,ethylcarbodimide, hydrochloride, polylactic acid, or PLGA.

Drainage catheter 104 may optionally be a flexible polymer drainagecatheter. Suitable materials for drainage catheter 104 include, forexample, PVC, low density polyurethane, PTFE, and silicone.

Drainage catheter 104 defines a central drainage lumen 112 and amembrane inflation lumen 114. Central drainage lumen 112 has an opendistal end, thus facilitating the suction of fluid located near thatend. Drainage catheter 104 also includes a plurality of drainageopenings 116 through which fluid is drawn into central drainage lumen112 and thereby removed from the pleural cavity. The plurality ofdrainage openings 116 may be drainage eyelets.

The distal end of membrane inflation lumen 114 is preferably closed, asillustrated in FIG. 1, so that inflation fluid can be maintained undercontrolled pressure for delivery to and removal from the inflatablemembrane 102. Membrane inflation lumen 114 is coupled for flow ofinflation fluid to and from an interior of inflatable membrane 102.Membrane inflation lumen 114 is specifically coupled for flow ofinflation fluid to and from inflatable tubelets 106. Membrane inflationlumen 114 may be formed integrally with a wall of central drainage lumen112 of drainage catheter 104.

Pleural drainage catheter system 100 is depicted having a tubulardrainage catheter 104 and a rounded inflatable membrane 102 wheninflated. However, other embodiments including differing configurationsand non-tubular shapes for drainage catheter 104 are contemplated. Forexample, the pleural drainage catheter system 100 may have any number ofshapes that can create space to facilitate and optimize fluid drainage,accommodation of organ shift due to lung lobectomies or enhancement ofother treatment options such as performing thoracoscopic procedures.Multiple and integrally connected channels or an integrated circularhoop catheter, all being enclosed by or formed in the inflatablemembrane 102, may be provided.

Additionally, as will be described later in greater detail, theconstruction of inflatable membrane 102 may be such that the twoopposing layers forming membrane 102 are made of materials or thicknessto provide a preferential curve or bias of the membrane when subject toa varying pressure. A curvature of inflatable membrane 102 may becreated, for example, by varying the pressure of inflation fluid, bychanging the size and orientation of inflatable tubelets 106, byproviding membrane materials with a physical curvature bias, or throughdissimilar membrane materials or thicknesses. The incorporation of suchpreferential bias or orientation into the membrane may enhance thetherapeutic benefit and clinical healing response by creating anaturally contouring shape around the lung which facilitates drainage ofcollected and pooling fluid.

Pleural drainage catheter system 100 as disclosed may be used as adiscreet device as described above, but preferentially is part ofcomplete pleural drainage system, which will be further describedherein.

The system 100 would solve the problem of inadequate pleural drainage byproviding multiple drainage channels during the continuous or selectiveinflation of the inflatable membrane. Additionally, the inflation of theinflatable membrane separates adjacent tissues limiting adhesion andfibrous formations. By controlling the timing sequence of the pleuraldrainage catheter system's inflation with respect to the pressurevariations of the inflation and concomitant suction applied to thepleural cavity, an additional therapeutic effect may be realized thateffectively exercises the lung tissue, thereby minimizing fluid leakageand pooling of fluid, which reduces the potential for infection tooccur. Further, the incorporation of a preferential bias or orientationinto the inflatable membrane may enhance the therapeutic benefit andclinical healing response. Additionally, the effectiveness of anadhesion limitation can be further enhanced by coating the inflatablemembrane with one of several anti-adhesion coatings.

FIGS. 2-5 depict an alternate exemplary embodiment of a pleural drainagecatheter system 200 in accordance with another aspect of the presentinvention. The pleural drainage catheter system 200 is configured toextend into a pleural cavity of a patient (not shown). As describedabove with respect to the embodiment of FIG. 1, pleural drainagecatheter system 200 includes an inflatable membrane 202 and a drainagecatheter 204 integrally coupled to inflatable membrane 202. Inflatablemembrane 202 defines eight tubelets 206 which when inflated define sixpassages 208, though alternate numbers can be provided. Tubelets 206extend in a direction angled at an acute angle with respect to an axisof drainage catheter 204.

Additionally, as described above with respect to the embodiment of FIG.1, drainage catheter 204 defines a central drainage lumen 212 and amembrane inflation lumen 214. Membrane inflation lumen 214 has a closeddistal end, so that inflation fluid can be maintained under controlledpressure for delivery to and removal from inflatable membrane 202.Drainage catheter 204 also includes a plurality of drainage openings 216through which fluid is drawn into central drainage lumen 212 and therebyremoved from the pleural cavity.

Inflatable membrane 202 also includes a plurality of drainage holes 218.Drainage holes 218 enable fluid on one external side of inflatablemembrane 202 to pass to an opposite external side of inflatable membrane202, so that the fluid can be drawn into central drainage lumen 212 andthereby removed from the pleural cavity. The plurality of drainage holes218 are illustrated as side-to-side drainage holes, though alternativespacings can be provided. The plurality of drainage holes 218 arelocated within the passages 208 defined by the tubelets 206 of theinflatable membrane 202. However, if alternatively shaped portions ofinflatable membrane 202 are inflated, drainage holes 218 may be locatedin areas consistent with such construction. The drainage holes 218 arelocated adjacent to the drainage catheter 204 to facilitate the removalof fluid from the pleural cavity of the patient. Drainage holes 218 maynonetheless be located anywhere on inflatable membrane 202. In such adesign, drainage holes 218 may operate in conjunction with passages 208to increase the drainage area covered by system 200 and to facilitatethe passage of fluid to drainage catheter 204. The shape and size ofdrainage holes 218 may be chosen to optimize passage of fluid todrainage catheter 204.

FIGS. 2 a, 3 a, and 3 b depict exemplary pleural drainage cathetersystem 200 in a deflated state. As described above with respect to theembodiment of FIG. 1, inflatable membrane 202 has a deflated state, inwhich the tubelets 206 are deflated. In this state, the two opposedlayers 220 and 222 of inflatable membrane 202 are positionedsubstantially adjacent one another. Even while not inflated, inflatablemembrane 202 still provides some means to track and drain fluid, byproviding a space between the tissue of the pleural cavity through whichfluid may pass. Additionally, even while not inflated, any therapeuticcoatings and/or agents on inflatable membrane 202 can be dispersed oractively delivered through contact of inflatable membrane 202 with thepleural tissue while inserted.

FIGS. 2 b, 4 a, and 4 b depict exemplary pleural drainage cathetersystem 200 in an inflated state. As described above with respect to theembodiment of FIG. 1, inflatable membrane 202 also has an inflatedstate, in which tubelets 206 are inflated. In this state, portions ofthe respective opposed layers 220 and 222, which form tubelets 206, arespaced apart from one another. The external surface of inflatablemembrane 202, which when inflated forms tubelets 206, also definespassages 208 between the tubelets 206. Though illustrated as parallelchannels, the design of passages 208 is dependent only on the spaceprovided between the deflated and inflated portions of membrane 202, andmay take any shape or size which facilitates the separation of tissueand/or the movement of fluid. The passages 208 may function as drainagechannels such that when inflatable membrane 202 is in the inflatedstate, passages 208 facilitate the movement of fluid along the externalsurface of inflatable membrane 202 to drainage catheter 204 for removalfrom the pleural cavity. Therapeutic coatings and/or agents can also bedispersed or actively and selectively dispended in the inflated statethrough contact of inflatable membrane 202 with the pleural tissue.

FIG. 5 further depicts exemplary pleural drainage catheter system 200.Membrane inflation lumen 214 of drainage catheter 204 has an openproximal end. As will be described in greater detail below, membraneinflation lumen 214 is coupled for flow of inflation fluid through theopen proximal end of membrane inflation lumen 214 to and from aninterior of inflatable membrane 202. Membrane inflation lumen 214 mayoptionally be coupled for flow of inflation fluid through the openproximal end of membrane inflation lumen 214 to and from inflatabletubelets 206. In this configuration, the open proximal end of membraneinflation lumen 214 will be coupled to an external inflation system. Theflow of inflation fluid through membrane inflation lumen 214 is thencontrolled by the external inflation system, as will be described later.

Membrane inflation lumen 214 is formed integrally with a wall of centraldrainage lumen 212 of drainage catheter 204. However, membrane inflationlumen may take any form within drainage catheter which keeps a flow ofinflation fluid within membrane inflation lumen 214 separate from a flowof fluid being removed through central drainage lumen 212. Additionally,while membrane inflation lumen is illustrated as being within drainagecatheter 214, a separate or adjacent membrane inflation lumen 214 can beprovided.

FIGS. 6-7 depict an exemplary embodiment of a pleural drainage cathetersystem 300 in accordance with an aspect of the present invention.Pleural drainage catheter system 300 includes an inflatable membrane 302and a drainage catheter 304 integrally coupled to inflatable membrane302. In this embodiment, drainage catheter 304 is located belowinflatable membrane 304 and is connected to inflatable membrane 304 suchthat inflatable membrane 302 covers a portion of the circumference ofdrainage catheter 304. However, it is contemplated that drainagecatheter 304 may be coupled to inflatable membrane 302 in otherconfigurations which similarly provide for a narrow insertion profile.Inflatable membrane 302 and drainage catheter 304 may be formed as onepiece, or may be affixed together by RF welding, heat staking, orsuitable adhesives.

As described in relation to the above embodiments, inflatable membrane302 may define one or more tubelets 306 which when inflated define oneor more passages 308. The passages 308 may function as drainage channelssuch that when inflatable membrane 302 is in the inflated state,passages 308 facilitate the movement of fluid along the external surfaceof inflatable membrane 302 to drainage catheter 304 for removal from thepleural cavity. Tubelets 306 may extend radially outward with respect toan axis of drainage catheter 304.

Drainage catheter 304 defines a central drainage lumen 312 and amembrane inflation lumen 314. Central drainage lumen 312 has an opendistal end to provide a passage for the removal of fluid from thepleural cavity of the patient. Membrane inflation lumen 314 also has anopen distal end, though its distal end is preferably closed so thatinflation fluid can be maintained under controlled pressure for deliveryto and removal from inflatable membrane 302. Membrane inflation lumen314 is formed integrally with a wall of central drainage lumen 312 ofdrainage catheter 304.

While FIGS. 6-7 illustrate the inflatable membrane 302 as planar inshape, the selected polymer material of inflatable membrane 302 can besuch that the system 300 will conform to the anatomical constraints ofthe pleural space. As depicted in FIGS. 10-12, which are describedbelow, the construction of inflatable membrane 302 may be such that thetwo opposing layers forming membrane 302 are made of materials orthickness to provide a preferential curve or bias of the membrane whensubject to a varying pressure. A preferential curve may be created ifone of the two opposing layers forming inflatable membrane 302 hasslightly less area than the other layer. A curvature of inflatablemembrane 302 may be created, for example, by varying the pressure ofinflation fluid, by changing the size and orientation of inflatabletubelets 106, by providing membrane materials with a physical curvaturebias, or through dissimilar membrane materials or thicknesses. Theincorporation of such preferential bias or orientation into the membranemay allow inflatable membrane 302 to conform to the shape of the pleuralcavity, and thereby enhance the therapeutic benefit and clinical healingresponse. Additionally, by controlling the inflatable tubelets 306 andtheir orientation, physical movement of drainage catheter 304 can becreated which provides a sweeping effect of the catheter across andthrough the pulmonary space as it is inflated and deflated. Bysequentially inflating and deflating tubelets 306 having differentthicknesses and differently sized channels, or by inflating anddeflating the tubelets 306 in stages, movement can be created whichre-positions the catheter from one area to another within the pleuralspace or alternatively, can translate the catheter from one area to anadjacent area with minimal irritation or disruption of tissue.

FIG. 8 depicts an exemplary embodiment of a pleural drainage cathetersystem 400 in accordance with another aspect of the present invention.Pleural drainage catheter system 400 includes an inflatable membrane 402and a drainage catheter 404 integrally coupled to inflatable membrane402. Drainage catheter 404 defines a central drainage lumen 412 and amembrane inflation lumen 414.

Drainage catheter 404 further defines a delivery lumen 424 through whicha medicament can be introduced into the pleural cavity and at least onedelivery opening through which the medicament is delivered into thepleural cavity from the delivery lumen 424. The delivery opening isillustrated at the end of delivery lumen 424; however, the deliveryopening may be located anywhere along delivery lumen 424. Additionally,delivery lumen 424 may have multiple delivery openings. Delivery lumen424 may be a therapeutic delivery lumen for introducing medicaments intothe pleural cavity. The medicaments introduced into the pleural cavitymay include antibiotics or antimicrobial agents. Suitable antibiotics orantimicrobial agents will be known to one of ordinary skill in the art.

While delivery lumen 424 is depicted as a separate lumen for thedelivery of therapeutic agents, this function may nonetheless beperformed by other lumens of drainage catheter 404. For example, aswould ordinarily be done during pleurodesis, central drainage lumen 412may provide for the delivery of therapeutic agents to the pleural cavityin addition to providing a channel for the removal of fluid from thepleural cavity. Further, while delivery lumen 424 is depicted as anintegral part of drainage catheter 424, it is contemplated that deliverylumen 424 could be defined by a separate catheter to optimize deliveryof therapeutic agents to affected areas of the pleural tissue. Deliverylumen 424 may be located on any part of inflatable membrane 402. Inaddition, inflatable membrane 402 may contain an active fluid membranethat under sustained pressurization or over-pressurization may elutefluid or drugs to provide therapy to surrounding tissue in the pleuralcavity to minimize inflammation or fibrous adhesion formation. Theelution of fluid or drugs can be controlled by a membrane valvemechanism that activates when a predetermined pressure is reached.Alternatively, the porous characteristics of the membrane can beadjusted so that at a prescribed pressure, controlled weeping or leakingthrough the membrane occurs to deliver a medicament from the membranepores. A variety of medicaments to therapeutically treat inflammation,pain, infection, and irritation can be delivered, such medicaments beingknown to one of ordinary skill in the art.

A benefit of medicament delivery through the drainage catheter or by anadditional therapeutic delivery lumen in the drainage catheter tube isthe ability to provide localized antibiotic or antimicrobial delivery,fibrin lysis therapy, or other analgesic therapy that can positivelyaffect pulmonary dynamics, function and healing.

FIG. 9 is a pleural drainage catheter system hierarchy in accordancewith an aspect of the present invention. Pleural drainage cathetersystem 500 includes an inflatable membrane 502 and a drainage catheter504 integrally coupled to inflatable membrane 502. Inflatable membrane502 may be a flexible polymer sealed membrane. Drainage catheter 504 maybe a flexible polymer catheter.

Inflatable membrane 502 may also include radiopaque edges or markers 510along the edges of inflatable membrane 502. The radiopaque markers 510are positioned to facilitate visualization of inflatable membrane 502during and after its insertion into the pleural cavity of a patient.Inflatable membrane 502 may further include an anti-adhesion coating 526on the external surface of inflatable membrane 502 to resist adhesion ofinflatable membrane 502 to tissue in the pleural cavity of a patient.Inflatable membrane 502 may further include a therapeutic coating 528configured to provide therapy to tissue in the pleural cavity of apatient.

Drainage catheter 504 optionally defines two or three separate lumens.In a double lumen option, drainage catheter 504 defines a centraldrainage lumen 512 and a membrane inflation lumen 514. In thisconfiguration, central drainage lumen 512 is the primary, or larger,lumen, and membrane inflation lumen 514 is the secondary, or smaller,lumen. However, membrane inflation lumen 514 need not be smaller thancentral drainage lumen 512; any size may be chosen for the lumens asnecessary for their proper function. Central drainage lumen 512 includesmultiple eyelet openings through which fluid is drawn into centraldrainage lumen 512 and thereby removed from the pleural cavity. Membraneinflation lumen 514 provides for active inflation and active deflationof inflatable membrane 502.

In a triple lumen option, drainage catheter 504 defines a centraldrainage lumen 512, a membrane inflation lumen 514, and a delivery lumen524. In this configuration, central drainage lumen 512 is the primary,or larger, lumen, and both membrane inflation lumen 514 and deliverylumen 524 are secondary, or smaller, lumens. However, the secondarylumens need not be smaller than central drainage lumen 512; any size maybe chosen for the lumens as necessary for their proper function. As withthe double lumen option, central drainage lumen 512 includes multipleeyelet openings through which fluid is drawn into central drainage lumen512 and thereby removed from the pleural cavity. Membrane inflationlumen 514 provides for active inflation and active deflation ofinflatable membrane 502. Additionally, a medicament can be introducedinto the pleural cavity of the patient through delivery lumen 524.

FIGS. 10-12 depict cross-sectional views of an exemplary embodiment ofan inserted pleural drainage catheter in accordance with an aspect ofthe present invention. FIG. 10 depicts a cross-sectional end view ofpleural drainage catheter system 600. Pleural drainage catheter system600 is depicted inserted into the pleural cavity 630 of a patient.Pleural drainage catheter system 600 may be inserted into the pleuralcavity 630 by means of a trocar system or other standard chest tubeinsertion techniques. Pleural drainage catheter system 600 includesinflatable membrane 602 and drainage catheter 604 integrally coupled toinflatable membrane 602. Inflatable membrane 602 is preferentiallycurved to conform to the anatomical constraints of the pleural cavity630. In FIG. 10, inflatable membrane 602 is depicted in a deflatedstate.

FIG. 11 depicts another cross-sectional end view of inserted pleuraldrainage catheter system 600. In FIG. 11, inflatable membrane 602 isdepicted in an inflated state. As will be discussed in detail below,inflatable membrane 602 of pleural drainage catheter 600 is inflated bythe passage of inflation fluid through the membrane inflation lumen andinto the inflatable portions or tubelets of inflatable membrane 602.This inflation fluid is provided by an inflation system which operatesto actively inflate and deflate inflatable membrane 602 using theinflation fluid.

FIG. 12 depicts a cross-sectional side view of inserted pleural drainagecatheter system 600. As in FIG. 11, inflatable membrane 602 is depictedin an inflated state.

FIG. 13 depicts an exemplary embodiment of a pleural drainage system 700in accordance with an aspect of the present invention. Pleural drainagesystem 700 is configured to deliver a therapeutic treatment to thepleural cavity 730 of a patient. Pleural drainage system 700 includes apleural drainage catheter system 701. Pleural drainage catheter system701 may include any of the features of the embodiments of pleuraldrainage catheter systems described above with reference to FIGS. 1-11.Pleural drainage catheter system 701 includes an inflatable membrane 702having a deflated state and an inflated state and a drainage catheter704 coupled to inflatable membrane 702. Drainage catheter 704 defines acentral drainage lumen having a plurality of drainage openings throughwhich fluid is drawn into the central drainage lumen from the pleuralcavity 730, and an inflation lumen coupled for flow of inflation fluidto and from an interior of inflatable membrane 702.

In a preferred embodiment, pleural drainage system 700 comprises acollection and inflation means 732 configured with multiple pump andpressure sensors including a suction system 734, a fluid collector 736,and an inflation system 738, which will be described in greater detailbelow. Collection and inflation means 732 is optimally easily removableor connectable to pleural drainage catheter system 701 in order to formpleural drainage system 700. Collection means 732 is optimally selfcontained and/or configured to function on battery or direct wall power.Collection means 732 is illustrated as including a suction system 734,fluid collector 736, and inflation system 738. However, one or more ofthe systems may be omitted from collection means 732 and in thatconfiguration may operate as a stand-alone system. Suction system 734 inmeans 732 may include a pump system to provide suction and pressuremonitoring to drainage catheter 704. Fluid collector 736 in means 732may be a receptacle for collecting fluid drained from pleural cavity 730by drainage catheter 704. Fluid collector 736 may be configured to beeasily removable and replaceable in collection means 732 for easydisposal of drained fluid. Inflation system 738 may include anotherpump/pressure system to provide modulated pressure and pressuredetection to inflatable membrane 702. Collection means 732 may includefurther pump and pressure detection systems to facilitate thedispensation of therapeutic agents into the pleural cavity 730 of thepatient.

Suction system 734 is connected to apply suction to the central drainagelumen of drainage catheter 704. This suction allows the central drainagelumen to draw fluid from the pleural cavity 730 into the drainage lumenof drainage catheter 704 through the drainage openings.

The benefit of suction system 734 applying suction to drainage catheter704 in combination with inflatable membrane 702 is the facilitation ofpleural drainage and thereby reduction of potential infection caused bytrapped fluid in pleural cavity 730 of the patient. In operation, fluidwhich collects adjacent to drainage catheter 704 due to the passagesformed by inflatable membrane 702. Fluid flows through the passages andis then drawn into drainage catheter 704 and removed from the pleuralcavity. Additionally, suction system 734 may be configured to monitorthe suction applied to the drainage lumen of drainage catheter 704.

Fluid collector 736 is coupled to receive fluid from the drainage lumenof drainage catheter 704. In this embodiment, fluid collector 736 isillustrated as coupled directly to drainage catheter 704. The fluid thatis drawn into drainage catheter 704 may then flow directly into fluidcollector 736 for collection and removal. Fluid collector 736 mayalternately be coupled to suction system 734. In this configuration,suction system 734 may cause the fluid to flow into the suction systembefore being deposited in fluid collector 736. Fluid collector 736 maybe formed integrally with suction system 734. However, fluid collector736 is optimally a separately removable fluid collector for easy removaland disposal of drained fluid.

Inflation system 738 may include a pump configured for active inflationand active deflation of inflatable membrane 702. Inflation system 738 isconnected to apply and modulate pressure to the inflation lumen ofdrainage catheter 704 and to deliver inflation fluid to the interior ofinflatable membrane 702 through the inflation lumen defined by drainagecatheter 704. Inflation fluid may be a liquid or gas. Suitable inflationfluids include air and saline solution, for example, but other inflationfluids can be substituted.

The suction applied by suction system 734 and the pressure modulationsapplied by the inflation system 738 may both be selectively engaged torun concurrently or discreetly. Preferably, both systems are selectivelyengaged as part of a therapeutic regimen to facilitate clinical healing.In one preferred embodiment, pleural drainage system 700 is activated intwo stages. In the first stage, which follows successful insertion ofpleural drainage catheter system 701, inflation system 738 is activatedto allow inflatable membrane 702 to deploy into the pleural space.Radiopaque markers (not shown) may be used to determine or confirm thelocation and successful deployment of inflatable membrane 702. In thesecond stage, after successful deployment of inflatable membrane 702 isconfirmed, inflation system 738 is switched into therapeutic mode, inwhich the active inflation and active deflation of inflatable membrane702 occurs in short, low pressure cycles over a pre-determined period oftime.

Additionally, drainage catheter 704 may selectively dispense therapeuticagents as part of this therapeutic regimen. Suitable therapeutic agentswill be known to one of ordinary skill in the art.

Upon insertion of pleural drainage catheter system 701 into theappropriately selected region of pleural cavity 730, inflatable membrane702 is discreetly and singularly inflated or connected to inflationsystem 738, which will then selectively inflate and then deflateinflatable membrane 702. The inflation/deflation sequence of inflatablemembrane 702 separates the bounding layers of tissue and createsfissures and channels through which the fluid can be drawn to thecentrally located drainage catheter 704. The collected and pooling fluidcan then be drawn out of the pleural cavity and into fluid collector 736by the suction applied to drainage catheter 704 by suction system 734.The timing of the inflation/deflation sequenced may be selected tooptimize treatment of the pleural cavity.

FIG. 14 shows a pleural drainage system hierarchy in accordance with anaspect of the present invention. Pleural drainage system 800 may includeany of the components described above with relation to FIG. 13. In apreferred embodiment, pleural drainage system 800 includes an electroniccontroller 840 coupled to either one or both of a suction system (notshown) and an inflation system 838. Electronic controller 840 may alsobe coupled to fluid collector 836. Fluid collector 836 may be adisposable chamber. Electronic controller operates and controls thevarious electronic and mechanical systems of pleural drainage system800.

Inflation system 838 is optionally a catheter pump drive systemcontaining an inflation fluid. Inflation system 838 includes a pump 842configured for active inflation and active deflation of an inflatablemembrane. Inflation system 838 may also include a sensor 844 configuredto sense the pressure of the inflation fluid. Inflation system 838 mayfurther include a maximum pressure check valve 846 configured to releaseinflation fluid from pleural drainage system 800 when a predeterminedpressure is achieved.

Pleural drainage system 800 may further include a number of electroniccomponents to be controlled by electronic controller 840. Pleuraldrainage system 800 may optionally include a scanner 848 for obtainingpatient identification information. Pleural drainage system 800 may alsoinclude a display 850. Display 850 may be an LCD display having agraphical user interface (GUI). Display 850 may also include systemcontrols configured to allow a user to control the operation of pleuraldrainage system 800. Pleural drainage system 800 may include a datastorage means 852 for storing information including patient data andbackup data. Data storage means 852 includes computer memory. Pleuraldrainage system 800 includes power means 854 including, for example, anA/C plug or batteries. Pleural drainage system 800 may include a datatransfer means 856. Data transfer means 856 may be a connection such asa wireless communications device or a computer-readable removable disk.Pleural drainage system 800 may also include user interface software 858to facilitate operation of pleural drainage system 800 and an audiblealarm 860 for alerting a user. An alarm may be activated in conditionswhen, for example, pleural drainage system 800 detects a leak in theinflatable membrane, pleural drainage system 800 has a low battery orwhen the therapeutic session is over.

Pleural drainage system 800 also includes a pressure sensor module 862.Pressure sensor module 862 is configured to monitor the pressure ofinflation fluid in the inflatable membrane. Pressure sensor module maybe further configured to measure the exerted pressure within the pleuralcavity. Pressure sensor module 862 may include a pressure sensor 864, aprocessor 866, and a sensor access probe 868.

The inflation system 838 and pressure sensor module 862 optimallyincorporate a feedback means to measure the exerted pressure within thepleural cavity. By measuring the pressure exerted on the inflatablemembrane within the pleural space, pleural drainage system 800 can beconfigured to determine the work output related to the exerted pressureas a function of the physiological conditions of the patient.

Additionally, as described below, the inflatable membrane may haveinflated portions of different sizes, shapes, and locations. System 800may further incorporate feedback means to measure the differentialpressure across multiple areas of the inflatable membrane within thepleural cavity. Measuring the differential pressure in areas that areinflated to different volumes may provide feedback on the response andclinical condition of the tissue and other structures adjacent theinflatable membrane.

By measuring the pressure response of the patient, an algorithm can thenbe configured to optimize the sequence and timing of the inflation anddeflation applied by inflation system 838 to the inflatable membrane.Additionally, inflation pressure exerted as well as duration ofinflation and deflation can be selectively optimized so as to improvethe healing response and pulmonary function of the patient.

FIG. 15 is a graph depicting the pressure within the pleural space of apatient in accordance with an aspect of the present invention. Thedisclosed pleural drainage system may be configured and used to measurethe pressure within the pleural space without restricting the flow inthe drainage catheter. The rate of decay of the pressure in the pleuralcavity correlates to the assessment of a patient airleak in the pleuralcavity. Accordingly, the disclosed pleural drainage system may be usedto monitor an airleak in a pleural cavity of a patient. Monitoring theairleak of the patient's pleural cavity can provide valuable informationregarding treatment and recovery of the patient. This information mayinclude providing the medical staff with increased knowledge andunderstanding on how a post-operative airleak is healing during patientrecovery. This may further lead to establishing reliable data forpattern recognition for multiple patients to assist a doctor or medicalpractitioner in the consideration of when to remove a chest tube. Thisinformation in turn may potentially shorten the length of hospital staya patient may require following thoracic surgery.

Airleaks within the pleural cavity are monitored by measuring the rateof pressure decay in the pleural cavity of a patient, correlating therate of pressure decay to an associated airleak, and generating anindicator showing a trend in the magnitude of the airleak in the pleuralcavity. As described above, the rate of exerted pressure decay in thepleural cavity of a patient may be measured using the disclosed pleuraldrainage system.

It has been discovered that the relationship of the trend in airleakresolution is proportional to the measured pressure decay and can beexpressed by the following relationship:

Q_(Airleak)α∫Pdt

where:

-   -   Q_(Airleak) is an extrapolated airleak,    -   P is a measured pressure, and    -   t is time.        Accordingly, the patient airleak correlates to the rate of        pressure decay in the pleural space of the patient.

FIG. 16 is a graph depicting the rate of pressure decay within thepleural space of a patient in accordance with an aspect of the presentinvention. Using the above correlation, the pleural drainage system isable to quantify the trend and rate of decay as a function of airleakover differing time intervals. Changes and resolution of the patientairleak as a function of clinical healing are detected by a reduction inthe measured pressure decay rate, and can then be correlated to areduced airleak by the above algorithm.

An indicator can be generated depending on the variation in patientairleak. For example, the change in pressure decay and proportionalcorrelation to airleak variation can be accumulated and the feedbackpresented by a varying trend analysis. The generated indicator mayinclude a simple light means where a reduction in airleak over adetermined period of time correlates to a change in the emitted light.According to one exemplary embodiment, this includes a progressive Redto Yellow to Green light indication. In this embodiment, the progressivechange in the light color provides the clinician with informationrelated to the reduction in the airleak and improvement of the overallpleural health of the patient.

It will be understood that pleural drainage systems of the presentinvention are not limited to the features described. Additional featuresof exemplary embodiments of pleural drainage systems are describedherein with reference to FIGS. 17-23.

In the exemplary embodiment illustrated in FIG. 17, a pleural drainagesystem 900 includes a suction system 902 and a fluid collector 904. Thesuction system 902 may be coupled to provide suction to a drainagecatheter (not shown). As will be described herein, suction system 902may generate suction using one or more pumps or may be coupled to anexternal source of suction (i.e., a hospital suction line) in order toprovide suction to the drainage catheter. Any suitable drainage cathetercan be selected for use with suction system 902.

Fluid collector 904 may be coupled to receive fluid from the drainagecatheter. As illustrated in FIG. 17, fluid collector 904 may be asub-component that is configured to be removed from suction system 902to facilitate the removal and/or disposal of fluid.

Suction system 902 includes a control panel 906 disposed on a frontsurface of suction system 902. Control panel 906 may include a pluralityof controls for operating pleural drainage system 900. Exemplarycontrols and indicators of control panel 906 are described withreference to FIG. 18.

Pleural drainage systems in accordance with the present inventionpreferably include a system on/off switch. In an exemplary embodimentillustrated in FIG. 18, control panel 906 includes an on/off switch 910.On/off switch 910 may be operable to activate or deactivate the suctionsystem 902 of the pleural drainage system 900. On/off switch 910 mayinclude an LED that indicates when the pleural drainage system 900 isactive. For example, the LED may continuously blink when the pleuraldrainage system is active, and may be turned off when the pleuraldrainage system is not active.

Pleural drainage systems may further include a vacuum suction indicator.In an exemplary embodiment, control panel 906 includes a vacuum suctionindicator 912, as illustrated in FIG. 18. Vacuum suction indicator 912may function when an external suction source is utilized by suctionsystem 902, or when suction is provided internally by suction system902. Vacuum suction indicator 912 may desirably indicate the targetvacuum pressure to be applied to the patient. For example, indicator 912may include four target pressures to be applied to the patient, e.g.,−10, −20, −30, −40 cmH₂O. Each of the four target pressures may beidentified by an LED on control panel 906, as illustrated in FIG. 18.The four target pressures represent one preferred embodiment but othertarget pressures, e.g., −5 up to −200 cmH₂O are also within theclinically significant range for the described device and may be addedor substituted. Additionally, while four target pressures are described,any number of target pressures can be selected.

The operator of pleural drainage system 900 may employ vacuum suctionindicator 912 to select a target pressure to be applied to the patient.For example, pleural drainage system 900 may include a mechanical dialregulator to allow an operator to mechanically adjust the targetpressure provided by suction system 902. Suction system 902 may thencontrol the suction provided to the patient based on the selected targetpressure.

Pleural drainage systems may further include a controller module forcontrolling the suction provided to a drainage catheter. The controllermodule preferably includes a vacuum sensor for measuring the negativepressure applied by the suction system.

In an exemplary embodiment, the controller module of pleural drainagesystem 900 includes a vacuum sensor S2, as illustrated in the schematicdiagram in FIG. 19. Vacuum sensor S2 measures the negative pressureprovided by suction system 902. Vacuum sensor S2 may further operate inconjunction with vacuum suction indicator 912 to indicate the measurednegative pressure. For example, as described above, indicator 912 mayinclude four LEDs that correspond to target pressures.

Pleural drainage system 900 may illuminate one of the LEDs of vacuumsuction indicator 912 when the measured pressure is within apredetermined range of the target pressure of the corresponding LED. Forexample, LEDS of vacuum suction indicator 912 optionally blink when thevacuum pressure measured by sensor S2 is within +/−3 cmH₂O of the settarget pressure. Further, the nearest corresponding LED to the settarget vacuum pressure outside the +/−3 cmH₂O tolerance range may be setto illuminate until the target set vacuum pressure is within range.

To accurately detect the range of negative pressures generated bysuction system 902, vacuum sensor S2 may optionally measure pressures inthe range from “0” to “−1” PSI (or approximately “0” to “−70.3 cmH₂O”).Suitable vacuum sensors for use with the present invention include ModelNo. HSCMRNN001PGAA3, provided by Honeywell International Inc., althoughother suitable vacuum sensors are optionally selected.

Pleural drainage systems may also include a patient pressure indicator.In an exemplary embodiment, control panel 906 includes a patientpressure indicator 916, as illustrated in FIG. 18. The operation andfunction of the patient pressure indicator will be described below. Theshape, size and configuration of the patient pressure indicator 916 canbe varied to provide any one of many shapes, sizes and configurations,depending on aesthetic preferences and the desired ornamentation of thedrainage system.

As described above, pleural drainage systems optionally employ analgorithm, such as the one described above, to determine a patient'sairleak. Pleural drainage system 900 may employ patient pressureindicator 916 as described above to indicate the patient airleak to anoperator.

As described above, pleural drainage systems preferably include apressure sensor. In an exemplary embodiment, the controller module ofpleural drainage system 900 includes a pressure sensor S3, asillustrated schematically in FIG. 19. Pressure sensor S3 may beconnected in line with the drainage catheter of the pleural drainagesystem in order to measure pressure in the patient line. The pressuresensor S3 is optionally configured to measure the peak pressure duringexpiration and inspiration of the patient at each breath cycle. System900 may further illuminate one or more of the LEDs of patient pressureindicator 916 that correspond with the range of pressure assigned tosuch LED, as will be described below.

Patient pressure indicator 916 includes three LEDs to provide indicationof a patient's pleural pressure, measured by pressure sensor S3, to anoperator of pleural drainage system 900, as illustrated in FIG. 20.Though FIG. 20 illustrates an embodiment having three LEDs, a smaller orlarger number of LEDs or other indicators are optionally selected. Also,the appearance (shape, size and configuration) of the indicators can bemodified depending on aesthetic and ornamental considerations.

For example, as described above, patient pressure indicator 916 mayinclude a green LED 918, a yellow LED 920, and a red LED 922, the colordifferences being indicated symbolically by cross-hatching in FIG. 20.LEDs 918-922 may be illuminated when the measured pressure, or ameasured or calculated pressure differential, is within certainthresholds. In an exemplary embodiment, patient pressure indicator 916activates a blinking green LED 918 to indicate that the pleural cavityis at optimum sub-atmospheric pressure, and/or that there is no patientairleak. Patient pressure indicator 916 may activate a blinking yellowLED 920 to indicate that a pleural cavity is at minimal positive and lowsub-atmospheric pressure, and/or that there may be no patient airleak.Finally, patient pressure indicator 916 may activate a blinking red LED922 to indicate that a pleural cavity is at positive pressure, and/orthat there is a patient airleak.

Presence of a patient airleak may be determined using the algorithmsdescribed above. Specifically, it may be determined based on variablesincluding one or more of a measured pressure, a change in measuredpressure over time, and other inputs based on the patient's condition ata particular time or over a particular period of time.

When no suction is provided by pleural drainage system 900, thethresholds for illuminating LEDs 918-922 may be determined based onexpected clinical patient pressures. For example, patient pressureindicator 916 may be configured to illuminate only the red LED 922 whenthe patient's pressure is +0.5 cmH₂O or greater, as illustrated in FIG.20A. Patient pressure indicator 916 may be configured to illuminate onlythe yellow LED 920 when the patient's pressure is between 0 and −3.90cmH₂O, as illustrated in FIG. 20C. Patient pressure indicator 916 may beconfigured to illuminate only the green LED 918 when the patient'spressure is −4.00 cmH₂O or less, as illustrated in FIG. 20E. Whilepatient pressure indicator 916 is illustrated as including pressurethresholds of −4 cmH₂O and +2 cmH₂O, it will be understood that anyother values can be selected for these thresholds, as described below.

When suction is provided by pleural drainage system 900, the pressurethresholds for illuminating LEDs 918-922 may be determined based on bothexpected clinical patient pressures and suitable pressure differentialsbetween the patient line and the fluid collector 904. For example, asdescribed above, the controller module of pleural drainage system 900may include a pressure sensor S3 for measuring a pressure in the patientline. The controller module may further include a pressure sensor S4 formeasuring a pressure in the fluid collector 904. The controller modulemay be operable to determine a pressure differential between the patientline and the fluid collector.

In such a configuration, patient pressure indicator 916 may beconfigured to illuminate only the red LED 922 when a decay in pressureis measured (corresponding to a patient airleak), as illustrated in FIG.20A. Patient pressure indicator 916 may be configured to illuminate onlythe yellow LED 920 when a minor or substantially no pressure decay ismeasured (corresponding to when there may or may not be an airleak), asillustrated in FIG. 20C. Patient pressure indicator 916 may beconfigured to illuminate only the green LED 918 when there is no decayin the pressure and no pressure differential (corresponding to nopatient airleak), as illustrated in FIG. 20E.

It will be understood that these thresholds are illustrative and notlimiting, and that intermediate ranges could be established betweenthese thresholds, such that patient pressure indicator 916 mayilluminate in five stages instead of three, for example. In this case,patient pressure indicator 916 may illuminate both red and yellow LEDs922 and 920, as illustrated in FIG. 20B. It may also illuminate bothyellow and green LEDs 920 and 918, as illustrated in FIG. 20D. Theseadditional conditions for LEDs 918-922 provide additional informationindicative of the status of a patient's air leak.

Again, the appearance of the patient pressure indicator 916 and LEDs918-922 can take a wide variety of forms while still providing anindication of the status of a patient. For example, the LEDs can bereplaced by other means for visually indicating the status of apatient's air leak. Also, the shape, orientation, position, and size ofthe indicators can be modified, and their positions with respect to oneanother can also be modified, depending on aesthetic considerationswhile providing the same function. Ornamental features of patientpressure indicator 916 are described separately in U.S. Design patentapplication Ser. No. 29/357,469, filed Mar. 12, 2010.

Pleural drainage systems in accordance with aspects of the presentinvention may further include a low battery indicator. In an exemplaryembodiment, control panel 906 includes a low battery indicator 924 asillustrated in FIG. 18. Low battery indicator 924 may be configured toblink when the pleural drainage system 900 has less than a predeterminedpower (such as 20% battery power for example) remaining.

Pleural drainage systems according to embodiments of this invention mayalso include an audible alarm. In an exemplary embodiment, control panel906 includes an audible alarm (not shown). The audible alarm may operatein conjunction with the low batter indicator 924, such that the audiblealarm beeps periodically when the battery power is low, or when thepleural drainage system 900 needs to be connected to AC power. Theaudible alarm may also operate in conjunction with the fluid connector904 to indicate when the fluid connector 904 is full and should beremoved/replaced.

Pleural drainage systems in accordance with aspects of the presentinvention may further include a fluid-clearing device. In an exemplaryembodiment, pleural drainage system 900 includes a fluid clearingdevice, as illustrated schematically in FIG. 19. The fluid clearingdevice removes fluid or blockages from within a patient tubeautomatically when a predefined pressure differential exists between themeasured pressure at the patient (from pressure sensor S3) and themeasured pressure within the fluid collector (from pressure sensor S4).Alternatively the fluid clearing device can be activated based on afixed or selectable timer.

The fluid-clearing device includes an accumulator and a vacuum pump P1,as illustrated schematically in FIG. 19. When the fluid-clearing deviceis activated, the accumulator will have its air volume drawn down to−600 cmH₂O negative vacuum pressure using vacuum pump P1. A vacuumsensor 51 inline with the fluid collector 904 may be used to determinethe pressure of the accumulator and shut off the pump P1 when theaccumulator reaches the desired negative pressure. The fluid-clearingdevice may also include a microcontroller for controlling the activationof the accumulator.

The accumulator may be closed off by a magnetic valve V1 in order tostore the energy (−600 cmH₂O) within the accumulator until the magneticvalve is signaled to activate. Valve V1 may be activated when thedifferential pressure measured between pressure sensor S3 and pressuresensor S4 reaches a predefined differential pressure, at which time thestored energy will be released from the accumulator while simultaneouslyopening a separate vent valve V2 to allow the fluid within the patienttube to flow into the fluid collector 904. Opening vent valve V2 mayallow differential pressure to enter at the patient tube, therebypreventing exposure of the patient to high negative pressure. The storednegative pressure from the accumulator will draw the fluid away from thepatient and into the fluid collector 904. Alternatively, the accumulatorstored pressure may be adjusted by the algorithm described above, andset point values other than −600 cmH₂O may be utilized as determined tobe most clinically relevant. Additionally, the accumulator storedpressure may be adjusted based on desired power usable by pump P1 andnecessary negative pressure for removing a blockage.

It may be desirable to clear the patient tube in order to assureaccurate volumetric measurement of the collected fluid by preventingfluid collected within the tube from not being recorded, which maycreate variability in the clinical assessment of the collected drainage.It may also provide clinical benefit by keeping the tube clear so as tofacilitate further drainage and to minimize the backpressure created toa patient trying to expel an air leak. This feature may also minimizecare and effort for the clinical staff.

Vacuum pump P1 may desirably be a diaphragm vacuum pump. The accumulatormay desirably be a 300 cc volumetric vessel accumulator for example.Other volumetric vessel capacities are optionally utilized.

Pleural drainage systems may further provide for mobile suction bysuction system 902. As described above, suction system 902 may providesuction independently, without attachment to an external suction source.Mobile suction by suction system 902 may be activated by way of auser-operated switch on control panel 906. As a mobile suction system,suction system 902 may provide −20 cmH₂O of suction, for example.

Pleural drainage systems in accordance with aspects of the presentinvention may further include an internal, rechargeable battery. In anexemplary embodiment, pleural drainage system 900 includes an internallithium-ion battery (not shown). The internal battery may be rechargedthrough a standard AC power connection. The internal battery may providepower for all of the electrical features of system 900, including butnot limited to the vacuum suction indicator 912, the patient pressureindicator 916, the audible alarm, and the fluid-clearing device. Theinternal battery may further provide power to operate suction system 902as a mobile suction system, as described above.

In order to optimize the functionality of a pleural drainage system suchas systems 700, 800, or 900, the pleural drainage catheter system of thepleural drainage system is optionally provided with additional features.

For example, FIGS. 21-23 depict another alternative exemplary embodimentof a pleural drainage catheter system 1000 in accordance with an aspectof the present invention. The pleural drainage catheter system 1000 isalso configured to extend into a pleural cavity of a patient (notshown). The pleural drainage catheter system 1000 includes an inflatablemembrane 1002 and a drainage catheter 1004 integrally coupled toinflatable membrane 1002. Pleural drainage catheter system 1000 is apleural drainage catheter system substantially as described with respectto the above exemplary embodiments, except that it includes additionalfeatures as described below.

Inflatable membrane 1002 defines one or more tubelets 1006 when in aninflated state. While FIG. 21 illustrates five such tubelets 1006extending outwardly from each side of drainage catheter 1004, it will beunderstood that fewer or more such tubelets can be provided. Tubelets1006 may be formed by selectively sealing the two opposed layers ofinflatable membrane 1002 to define the one or more tubelets 106.

The tubelets 1006 may be provided in the form of substantially straightstructures, as illustrated, or in other curved or angled shapes to forminflatable ribs. While tubelets 1006 are illustrated as primarilycylindrical in shape, it will be understood that tubelets 1006 may haveother shapes, as desired. Respective tubelets 1006 may have differentlengths and/or cross-sectional areas, such that respective tubelets 1006fill different volumes when inflatable membrane 1002 is inflated. Asillustrated in FIGS. 21 and 22, it may be desirable that tubelets 1006toward the center of inflatable membrane 1002 be larger than tubelets1006 formed toward the periphery of inflatable membrane 1002.Additionally, one or more tubelets 1006 may be oriented to extend inother directions such as in a direction parallel to that of the drainagecatheter 1004. As illustrated in FIGS. 22 and 23, a tubelet 1006 runsadjacent to drainage catheter 1004 and crosses other tubelets 1006. Thetubelets 1006 that cross each other may, or may not, be in fluid flowcommunication with each other.

One or more tubelets 1006 may also include enlarged portions 1007.Enlarged portions 1007 have larger cross-sectional areas than tubelets1006. One or more enlarged portions 1007 may be formed on at least onetubelet 1006. While enlarged portions 1007 are illustrated as primarilyhemispherical in shape, it will be understood that enlarged portions1007 may have other shapes or sizes, as desired. Respective enlargedportions 1007 may have different cross-sectional areas such thatrespective enlarged portions 1007 fill different volumes when inflatablemembrane 1002 is inflated. As illustrated in FIGS. 21 and 23, it may bedesirable that enlarged portions 1007 be formed on both sides ofinflatable membrane 1002, and be formed in the center of inflatablemembrane 1002.

Tubelets 1006 and enlarged portions 1007 define one or more passages1008, as described above. The passages 1008 may function as drainagechannels such that when inflatable membrane 1002 is in the inflatedstate, passages 1008 facilitate the movement of fluid along the externalsurface of inflatable membrane 1002 to drainage catheter 1004 forremoval from the pleural cavity. Although not shown, drainage holes likeholes 218 may be formed in the inflatable membrane 1002.

The catheter system 1000 also solves the problem of inadequate pleuraldrainage by providing multiple drainage channels during the continuousor selective inflation of the inflatable membrane 1002. Additionally, asdescribed above, the inflation of inflatable membrane 1002 separatesadjacent tissues limiting adhesion and fibrous formations. Specifically,forming tubelets 1006 having different shapes, sizes, andcross-sectional areas may advantageously further separate or dissectadjacent tissues and limit adhesion and fibrous formations, and enhanceand facilitate better drainage of the pleural cavity. Further, enlargedportions 1007 may be positioned on inflatable membrane 1007 to providepressure to specific areas of the pleural cavity, such as specific areasof loculations, thereby better separating tissue or providing animproved therapy. Enlarged portions 1007 may further be centrallylocated at the drainage catheter 1004 of system 1000, such as shown inFIG. 22, thereby facilitating inflation, deployment, retrieval, andretraction of system 1000. One or both of tubelets 1006 and enlargedportions 1007 can also be fabricated with a membrane material thatpermits the release of medicaments at controlled rates and pressures, asdescribed above.

Systems and methods according to aspects of this invention can be usedbeneficially in the treatment of various physiological indications andconditions. For example, in the United States, approximately 1,200,000patients develop pneumonia annually. Of these, approximately 40% developEmpyema. Further, approximately 5% of all pneumonia patients, or 60,000patients, develop para-pneumonic effusion, and require an extendedhospital stay and treatment.

The total charges for such treatment are well beyond the range of$60,000-$100,000 per patient. The length of a hospital stay for apatient with para-pneumonic effusion may range from 17-24 days fornon-surgically treated patients and 9-13 days for surgically treatedpatients. Data indicates that hospitals such as Vanderbilt MedicalCenter, University of California Irvine Healthcare, and Emory's CrawfordLong Hospital receive between 30-50 patients per year requiringtreatment for advanced loculated Empyema.

Treatment for pleural empyema generally requires the removal of infectedfluid from the pleural cavity of an affected patient. By utilizingsystems and methods according to exemplary embodiments of thisinvention, suction can be applied to a larger region of the pleuralcavity. Consequently, and often, fluid that is otherwise trapped in thepleural space can be removed by the suction catheter. Becauseparapneumonic effusions can become infected and progress to more chronicconditions and potentially death, the reduction of such effusionsaccording to aspects of this invention can provide significant benefits.Additionally, systems and methods according to aspects of this inventioncan provide alternative ways to monitor an airleak. Such alternativesare believed to be especially beneficial in circumstances wheresignificant clinical limitations to a patient may result from measuringlow flows or by limiting the flow area through which the airflow mustpass.

Disclosed embodiments of pleural drainage systems provide the clinicalbenefit of correlating measured pressures within the pleural space andwithin the inflatable membrane so as to selectively optimize thetreatment regimen, such as by using a control algorithm, and thereforeproviding the preferred pulmonary therapy and healing response.Additionally, the benefit of a suction system according to exemplaryembodiments that apply suction to a pleural drainage catheter combinedwith an inflatable membrane is the facilitation of pleural drainage andthe associated reduction of potential infection caused by trapped fluid.

Another benefit of embodiments of the disclosed pleural drainage systemis the means to measure the rate of pressure decay within the pleuralspace of the patient and correlate this measured response to anassessment of a patient airleak. This feature, whether used with orinstead of direct measurements of an airleak, provides an alternativethat allows the user to correlate the measured rate of pressure decay toan associated airleak without the need to restrict the flow or toincorporate an additional flow sensor.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

1. A pleural drainage catheter system configured to extend into apleural cavity of a patient and to drain fluid from the pleural cavityof the patient, said pleural drainage catheter system comprising: aninflatable membrane comprising two opposed layers formed from abio-compatible material, the inflatable membrane having a deflated statein which the layers are positioned substantially adjacent one anotherand an inflated state in which at least portions of the respectivelayers are spaced from one another, an external surface of theinflatable membrane defining one or more passages that facilitate themovement of fluid along the external surface for removal from thepleural cavity when the inflatable membrane is in the inflated state;and a drainage catheter integrally coupled to the inflatable membrane,the drainage catheter defining a drainage lumen, a plurality of drainageopenings through which fluid is drawn into the drainage lumen from thepleural cavity, and an inflation lumen coupled for flow of inflationfluid to and from an interior of the inflatable membrane.
 2. The pleuraldrainage catheter system of claim 1, said drainage catheter furtherdefining a delivery lumen through which a medicament can be introducedto the external surface of the inflatable membrane.
 3. The pleuraldrainage catheter system of claim 2, wherein the inflation lumen definesthe delivery lumen, and the medicament is introduced through theinflatable membrane when the inflatable membrane is pressurized via theinflation lumen.
 4. The pleural drainage catheter system of claim 1,wherein portions of the layers of the inflatable membrane define one ormore tubelets when the inflatable membrane is in the inflated state. 5.The pleural drainage catheter system of claim 4, wherein the one or moretubelets extend in a direction angled with respect to an axis of thedrainage catheter.
 6. The pleural drainage catheter system of claim 5,wherein the one or more tubelets extend in a direction substantiallyperpendicular to an axis of the drainage catheter.
 7. The pleuraldrainage catheter system of claim 4, further comprising plural tubelets,wherein at least two of the tubelets have different cross-sectionalareas when the inflatable membrane is in the inflated state.
 8. Thepleural drainage catheter system of claim 4, further comprising pluraltubelets, wherein at least two of the tubelets have differentcross-sectional shapes when the inflatable membrane is in the inflatedstate.
 9. The pleural drainage catheter system of claim 4, wherein across-sectional shape of at least one of the one or more tubelets iscylindrical.
 10. The pleural drainage catheter system of claim 4,wherein at least one of the one or more tubelets includes an enlargedportion having a larger cross-sectional area than the at least onetubelet when the inflatable membrane is in the inflated state.
 11. Thepleural drainage catheter system of claim 4, wherein the drainagecatheter is configured to move within the pleural cavity by a stagedinflation and deflation of the one or more tubelets.
 12. The pleuraldrainage catheter system of claim 1, the drainage lumen of the drainagecatheter having an open distal end and the inflation lumen of thedrainage catheter having a closed distal end.
 13. The pleural drainagecatheter system of claim 1, the inflatable membrane defining a drainageopening for the flow of fluid from one side of the inflatable membraneto an opposite side of the inflatable membrane.
 14. The pleural drainagecatheter system of claim 1, wherein the one or more passages defined bythe external surface of the inflatable membrane each provides a channelthat facilitates the movement of fluid along the external surface whenthe inflatable membrane is in the inflated state.
 15. The pleuraldrainage catheter system of claim 1, further comprising a coating on theexternal surface of the inflatable membrane, the coating beingconfigured to resist adhesion to tissue in the pleural cavity or toprovide therapy to the tissue.
 16. The pleural drainage catheter systemof claim 1, the inflatable membrane comprising a radiopaque markerpositioned to facilitate visualization of the inflatable membrane duringand after its insertion into the pleural cavity of the patient.
 17. Thepleural drainage catheter system of claim 1, the inflatable membranehaving a preferential curve when it is in the inflated state.
 18. Thepleural drainage catheter system of claim 1, the inflation lumen of thedrainage catheter being formed integrally with a wall of the drainagelumen of the drainage catheter.
 19. A method for monitoring an airleakin a pleural cavity of a patient, the method comprising the steps of:measuring a rate of pressure decay in the pleural cavity of the patient;correlating the rate of pressure decay to an associated airleak of thepleural cavity of the patient according to the following formula:Q_(Airleak)α∫Pdt where: Q_(Airleak) is an extrapolated airleak P is ameasured pressure t is time; and generating an indicator showing a trendin the magnitude of the airleak of the pleural cavity.
 20. The method ofclaim 19, wherein said generating step comprises generating aprogressive Red to Yellow to Green light indication of the trend in themagnitude of the airleak.
 21. A pleural drainage system configured todeliver a therapeutic treatment to the pleural cavity of a patient, saidsystem comprising: a pleural drainage catheter system including aninflatable membrane having a deflated state and an inflated state, thepleural drainage catheter system also including a drainage cathetercoupled to the inflation membrane, the drainage catheter defining adrainage lumen, a plurality of drainage openings through which fluid isdrawn into the drainage lumen from the pleural cavity, and an inflationlumen coupled for flow of inflation fluid to and from an interior of theinflatable membrane; a suction system coupled to the drainage catheterof the pleural drainage catheter system and connected to apply suctionto the drainage lumen of the drainage catheter and to draw fluid intothe drainage lumen of the drainage catheter through the drainageopenings defined by the drainage catheter; a fluid collector coupled toreceive fluid from the drainage lumen of the drainage catheter; and aninflation system coupled to the drainage catheter of the pleuraldrainage catheter system and connected to apply pressure to theinflation lumen of the drainage catheter and to deliver inflation fluidto the interior of the inflatable membrane through the inflation lumendefined by the drainage catheter.
 22. The pleural drainage system ofclaim 21, said suction system being configured to monitor the suctionapplied to the drainage lumen of the drainage catheter.
 23. The pleuraldrainage system of claim 21, further comprising an electronic controllercoupled to at least one of the suction system and the inflation system.24. The pleural drainage system of claim 21, said inflation systemcomprising a pump configured for active inflation and active deflationof the inflatable membrane.
 25. The pleural drainage system of claim 21,said inflation system comprising a sensor configured to sense thepressure of the inflation fluid.
 26. The pleural drainage system ofclaim 21, said inflation system comprising a maximum pressure checkvalve configured to release inflation fluid from the pleural drainagesystem when a predetermined pressure is achieved.
 27. The pleuraldrainage system of claim 21, further comprising a scanner for obtainingpatient identification information.
 28. The pleural drainage system ofclaim 21, further comprising a display including at least one of a userinterface and system controls.
 29. The pleural drainage system of claim21, further comprising a memory for storing at least one of patient dataand backup data.
 30. The pleural drainage system of claim 21, theinflatable membrane comprising two opposed layers formed from abio-compatible material, the layers being positioned substantiallyadjacent one another in the deflated state and at least portions of therespective layers being spaced from one another in the inflated state.31. The pleural drainage system of claim 21, further comprising aconnection for the transfer of data to and from the pleural drainagesystem.
 32. The pleural drainage system of claim 21, further comprisingan audible alarm.
 33. The pleural drainage system of claim 21, saidinflation system being configured to monitor the pressure of inflationfluid in the inflatable membrane and to measure the exerted pressurewithin the pleural cavity.
 34. The pleural drainage system of claim 33,further comprising a pressure sensor module having a pressure sensor, aprocessor, and a sensor access probe.
 35. A pleural drainage systemcomprising: a drainage catheter defining a drainage lumen and at leastone drainage opening through which fluid is drawn into the drainagelumen from a pleural cavity; a suction system coupled to apply suctionto the drainage lumen in order to draw fluid into the drainage lumenthrough the at least one drainage opening; a fluid collector coupled toreceive fluid from the drainage lumen of the drainage catheter; apressure sensor coupled to the suction system and positioned for sensinga pressure in the pleural cavity; a processor coupled to receive asignal from the pressure sensor based on the sensed pressure in thepleural cavity; and a plurality of indicators coupled to the processorand configured to visually indicate a status corresponding to the sensedpressure in the pleural cavity to an operator, wherein the processor isconfigured to selectively activate the plurality of indicators suchthat: a first indicator of the plurality of indicators is activated whenthe sensed pressure is within a first predefined range, a secondindicator of the plurality of indicator is activated when the sensedpressure is within a second predefined range, and a third indicator ofthe plurality of indicators is activated when the sensed pressure iswithin a third predefined range.
 36. The pleural drainage system ofclaim 35, wherein the first, second, and third predefined ranges arebased on predefined expected pressures for the pleural cavity.
 37. Thepleural drainage system of claim 35, wherein the first, second, andthird predefined ranges are based on predefined pressure differentialsbetween the pressure in the pleural cavity and a pressure applied by thesuction system.
 38. The pleural drainage system of claim 35, furthercomprising a fluid-clearing device for clearing fluid from the drainagecatheter of the pleural drainage system.
 39. The pleural drainage systemof claim 38, wherein the fluid clearing device comprises a pump and anaccumulator in fluid communication with the pump.
 40. The pleuraldrainage system of claim 33, wherein the processor is further configuredto selectively activate the plurality of indicators such that: the firstindicator and the second indicator of the plurality of indicators areactivated together when the sensed pressure is within a fourthpredefined range, and the second indicator and the third indicator ofthe plurality of indicators are activated together when the sensedpressure is within a fifth predefined range.
 41. A pleural drainagesystem comprising: a drainage catheter defining a drainage lumen and atleast one drainage opening through which fluid is drawn into thedrainage lumen from a pleural cavity; a suction system coupled to applysuction to the drainage lumen in order to draw fluid into the drainagelumen through the at least one drainage opening, the suction systemincluding a pump, an accumulator in fluid communication with the pump,and a valve coupled between the accumulator and the drainage catheter;and a fluid collector coupled to receive fluid from the drainage lumenof the drainage catheter; wherein the pump is configured to generate anegative pressure in the accumulator, the valve is configured to openwhen there is a blockage between the pleural cavity and the fluidcollector, and the opening of the valve causes the negative pressure inthe accumulator to be applied to the drainage catheter such that theblockage is drawn into the fluid collector.